Adjustable brake shoe



swt. 24, 1940. s SCHNELL 2,215,568

ADJUSTABLE BRAKE SHOE Filed July 13. 1939 I /n Pen/orf Patented Sept. 24, 1940 ADJUSTABLE BRAKE SHOE Steve Schnell, Overland, Mo., assigner to Wagner Electric Corporation, vSt. Louis, Mo., a corporation of Delaware Application July 13, 1939, Serial No. 284,187

14 Claims.

My invention relates to brakes and more particularly to a. brake shoe and adjusting means therefor to compensate for lining wear.

One of the objects of my invention is to provide adjusting means for automatically maintaining both the toe end and the heel end of a pivoted brake shoe a predetermined distance from the drum when the shoe is in off position.

Another object of my invention is to provide automatic adjusting means for a brake shoe which is so constructed that the drum engaging portion thereof adjacent the heel is free to be forced into engagement with the drum by a circumferential movement of the shoe, said adjusting means being capable of simultaneously adjusting both the heel end and the toe end so that the drum engaging portion of the entire shoe will be maintained at a constant distance from the drum when the shoe is disengaged.

Other objects of my invention will become apparent from the following description taken in connection with the accompanying drawing in which Figure 1 is a side view of a portion of a brake assembly showing a brake shoe and an adjusting means therefor embodying my invention; Figure 2 is a cross-sectional View takenl on the line 2-2 of Figure 1 showing the shoe mounting; and Figures 3, 4, and 5 are cross-sectional views taken on the lines 3-3, 4--4 and 5-5, respectively, of Figure 1 showing details of the adjusting mechanism.

Referring to the figures in detail, I have shown my automatic adjusting means associated with a particular type of brake shoe but it is to be understood that it can be associated with other brake shoe constructions wherein it is found desirable to adjust both the heel end and the toe end of said shoe by a single means in order to compensate for wear of the lining. The particular brake shoe construction shown comprises a web I provided at its lower end with an arcuate slot 2 for receiving a bearing member 3 eccentrically mounted on an anchor pin 4 carried by the backing plate 5. The

slot 2 permits the web to have limited circumferential movement but restrans the end of the web from radial movement toward the drum. The web is formed with a continuous flange 6 which carries lining 1. The portion of the web from an intermediatepoint to the pivoted end is provided with a slot 8 and a saw cut 9 in order to free a portion I0 of the web from the main part of the of the web. The bearing member 3 for the shoe (Cl. 18S-79.5)

has pivotally mounted thereon on opposite sides of the web two arms II which carry at their free ends a pin I2 for engagement with a recess I3 on the free end of the web portion I0. rIfhe shoe is shown as actuated into engagement with the 5 drum I4 by means of a iiuid motor I5.

When the drum is rotating in the direction indicated by the arrow and the shoe is engaged with the drum, the shoe will have slight circumferential movement with the drum as permitted 10 by the arcuate slot 2. This circumferential movement of the shoe will cause the web portion I0 to rotate the arms II and because of their angular relation to the direction of movement of the shoe, the free end of the web portion I0 will be 15 forced outwardly toward the drum, thus causing the lining carried by the web portion IIl to be applied to the drum with a greater force than would be the case if the web portion I0 were integral with the main part of the web I of the 20 shoe. The shoe is thus capable of producing a greater braking action because a part of the force tending to move the shoe with the drum is transferred into a radial pressure on the heel portion of the lining which is free to move out- 25 wardly.

In accordance with my invention I have provided means for automatically and simultaneously adjusting the off positions of both the toe end of the brake shoe and the heel end of the brake 30 shoe in order to compensate for wear of the lining. The construction I employ comprises a lever I6 which is pivotally mounted intermediate its ends to the web I of the shoe by means of a bolt Il having'an eccentric portion upon which the lever 35 is mounted in order to provide for adjustment of the pivotal axis of the lever with respect to the web. The upper arm I8 of the lever is provided with a projection I9 extending through an opening 20 in the lining carrying flange 6 and lining 1 of the shoe and having its outer end surface ush with the lining surface. The arm I8 cooperates with a stop 2I carried by the backing plate, this stop determining the distance that the shoe can be withdrawn from the drum by means of the 45 retractile spring 22 when the uid motor I5 is released.

The web I carries a. pin 23 formed with a V- shaped groove 24 for receiving a V edge 25 on a wedge 26 which is interposed-between a portion 21 50 on arm I8 of the lever I6. The Wedge is held in position by a spring 28 having one of its ends connected to the end of pin 23 and its other end web. A spring 3I is connected to the wedge and to the lever for moving the wedge relatively to the portion 21 on arm I8 of the lever and pin 23 whenever the lever is moved relative to the pin. A shoulder 32 is provided on the wedge for engagement with the portion 2li on arm I8 to limit the extent of movement of the wedge under the action of spring 3|. The lower arm 33 of the f lever carries a pin 34 which extends into the lower end of the slot 8 of the web of the shoe for engagement with the web portion IIJ.

When the adjusting mechanism just described is mounted on the shoe, the shoe is iirst applied to the drum and then the lever is adjusted by means of the pin I'I so the end surface of extension I 9 on the upper arm of the lever engages the drum and the pin 34 on the lower arm of the lever engages the portion I0 of the web. The stop 2l is next positioned so that when the shoe is released, the lining will have the desired clearance with respect to the drum, the shoe being released by pivotal movement about the anchor pin 8 which is adjusted to give proper clearance at the heel of the shoe. When the lining on the shoe begins to wear as a result of braking action, the levr I6 will be moved in a counter-clockwise direction about the pivot pin I1 due to the fact that the extension I9 is not worn as rapidly as the lining and, therefore, will be pushed back even with the lining as the liningwears. Whenever there is any relative movement between the upper arm I 8 of the lever and the web, the wedge 26 will take a new position under the operative action of the spring 3| and this new position will be maintained by the spring 28. Since the lever moves relatively to the shoe as the lining wears, the engagement of the lever with the stop 2l will not permit the shoe to move away from the drum as far as it did before and thus the lining wear will be compensated for. As arm I8 is moved due to lining wear over the toe portion of the shoe, there will also be simultaneous movement of the lower arm 33 toward the drum which will adjust the web portion I0 with respect to the main body of the web to compensate for wear of the lining thereon. It is thus seen that whenever there is automatic adjustment of the toe of the shoe to compensate for lining wear, there will be simultaneous adjustment of the heel end of the shoe. It may happen that the rate of wear of the lining at the toe end of the shoe will be greater or less than that at the heel end but this can be compensated for by properly proportioning the lengths of the arms 33 and I8.

It is to be noted that the entire adjusting mechanism is simple in construction and is carried entirely by the brake shoe with the exception oi stop 2| which is carried by the backing plate. Due to the fact that the adjusting mechanism is carried by the shoe and no adjustment takes place except when the lining wears, the mechanism is not affected by expansion and contraction of the drum during braking action.

Being aware of the possibility of modifications in the particular structure herein described without departing from the fundamental principles of my inventionl I do not intend that its scope be limited except as set forth by the appended claims.

Having fully described my invention, what I claim as new and 'desire to secure by .Letters Patent of the United States is:

1. In braking apparatus, a support, a brake drum, a brake shoe mounted on the support and provided with drum engaging means. and automatically operable means for maintaining the ofi position clearance between the drum and said drum engaging means substantially constant. said means comprising a lever pivotally carried by the shoe and being so movable as a result of wear of the drum engaging means that different parts of the lever will cause circumferentially spaced apart portions of the drum engaging means to be simultaneously adjusted toward the drum.

2. In braking apparatus, a support, a brake drum, a brake shoe mounted on the support and provided with drum engaging means, and automatically operable means for maintaining the off position clearance between the drum and said drum engaging means substantially constant, said means comprising a lever pivotally mounted intermediate its ends on the shoe and so cooperating with the drum when the shoe is engaged therewith that it will be moved relatively to the shoe as the result of wear of the drum engaging means, means for causing one end of said lever to adjust the oi position of one portion of the drum engaging means toward the drum, and means for causing the other end of said lever to adjust the ofi position of another portion of the drum engaging means toward the drum.

3.' In braking apparatus, a support, a brake drum, a brake shoe mounted on the support and provided with drum engaging means, and automatically operable means for maintaining the 01T position clearance between the drum and said drum engaging means substantially constant, said means comprising a lever pivotally mounted intermediate its ends on the shoe and so cooperating with Lhe drum when the shoe is engaged therewith that it will be moved relatively to the shoe as the result of wear of the drum engaging means, means for causing one end of said lever to adjust the off position of one portion of the drum engaging means toward the drum, means for causing the other end of said lever to adjust the oi position of another portion of the drum engaging means toward the drum, and wedging means for maintaining said lever and shoe in their relatively adjusted positions.

4. In braking apparatus comprising a support, a brake drum, and a brake shoe pivotally mounted at one end on the support for cooperation with the drum, said shoe having the lining carrying part thereof which is adjacent the mounted end portion movable relatively to the body oi the shoe and toward the drum when the shoe is applied, automatically operable means associated with the shoe and the support for maintaining a substantially constant off position clearance between the unmounted end of the shoe and the drum and between the lining carrying part adjacent the mounted end of the shoe and the drum as the lining on said shoe wears.

5. In braking apparatus comprising a support, a brake drum, and a brake shoe pivotally mounted at one end on the support for cooperation with the drum, said shoe having the lining carrying part thereof which is adjacent the mounted end movable relatively to the body of the shoe and toward the drum when the shoe is applied, automatically operable means associated with the shoe and the support for maintaining a substantially constant off position clearance between the unmounted end of the shoe and the drum and between the relatively movable lining carrying part of the shoe and the drum as the lining on said shoe wears, said means comprising a lever pivotally carried by the body of the shoe and movable relatively to the shoe only when lining wear occurs.

6. In braking apparatus comprising a support, a brake drum, and a brake shoe pivotally mounted at one end on the support for cooperation with the drum, said shoe having the lining carrying part thereof which is adjacent the mounted end movable relatively to the body of the shoe and toward the drum when the shoe is' applied, automatically4 operable means' associated with the shoe and the support for maintaining a substantially constant oi position clearance between the unmounted end of the shoe and the drum and between the' relatively movable lining carrying part of the shoe and the drum as the lining on said shoe wears, said means comprising a lever pivotally mounted intermediate its ends on the body of the shoe, means for moving the lever relatively to the shoe as the lining wears, means for causing one end of said lever when moved to thereby adjust the off position of the unmounted end of the shoe toward the drum and means for causing the other end of the lever when moved to thereby adjust the 01T position of the lining carrying part adjacent the mounted end of the shoe toward the drum. c

7. In braking apparatus comprising a support, a brake drum, and a brake shoe pivotally mounted at one end on the support for cooperation with the drum, said shoe having the lining carrying part thereof which is adjacent the mounted end movable relatively to the body of the shoe and toward thedrum when the shoe is applied, automatically operable means associated with the shoe and the support for maintaining a substantially constant off position clearance between the unmounted end of the shoe and the drum and between the relatively movable lining carrying part of the shoe and the drum as the lining on said shoe Wears, said means comprising a lever pivotally mounted intermediate its ends on the body of the shoe, means for moving the lever relatively to the shoe as the lining wears, means for causing 'one end of said lever when moved to thereby adjust the "oi position of the unmounted end of the shoe toward the drum, means for causing the other end of the lever when moved to thereby'adjust the off position of the lining carrying part adjacent the mounted end of the shoe toward the drum and wedging means for maintaining the lever and the shoe in their relatively adjusted positions.

8. In braking apparatus, a support, abrake drum, a brake shoe `mounted on the support, said shoe comprising a web mounted at one end for pivotal movement and for circumferential movement, drum engaging means carriedby the web and comprising a part secured to the web from an intermediate point to the unmounted end thereof and another part extending over the web from the mounted end toward an lintermediate point and free to move relatively to the web and toward the drum, means for applying an outward acting force to said free part when the shoe is applied to the drum, and automatically operable adjusting means for simultaneously maintaining the off position clearance of both parts of the drum engaging means substantially constant as said means wears.

-9. In braking apparatus, a support, aV brake drum, a brake shoe mounted on the support, said shoe comprising a web mounted at one end for pivotal movement and for circumferential movement, drum engaging means carried by the web and comprising a part secured to the web from an intermediate point to the unmounted end thereof and another part extending over the web from the mounted end toward an intermediate point and free to move relatively to the'web and toward the drum, means for applying an outward acting force to said free' part when the shoe is applied to the drum, and automatically operable adjusting means for simultaneously maintaining the off position clearance on both parts of the drum engaging means substantially constant as said means wears, said adjusting means comprising a lever pivotally mounted intermediate its endsl on the web and having a portion engageable with 'the drum only when the shoe is applied, cooperating means between one end of said lever and the support for adjusting the off position of the unmounted end of the shoe toward the drum, and connecting, means between the other end of the lever and the free portion of the drum engaging means for adjusting the oi position of said free portion of the drum engaging means toward the drum.

l0. In braking apparatus, a support, a brake drum, a brake shoe mounted on the support, said shoe comprising a web mounted at one end for pivotal movement and for circumferential movement, drum engaging means carried by the web and comprising a part secured to the web froman intermediate point to the unmounted end thereof and another part extending over the web from the mounted end toward an intermediate point and freey to move relatively to the web and toward the drum, means for applying an outward acting force to said free part when\the shoe is applied to the drum, and automatically operable adjusting means for simultaneously maintaining the off position clearance of both parts'of the drum engaging means substantially constant as said means wears, said adjusting means comprising a lever pivotally mounted intermediate its ends on the web and having a portion engageable with the drum only when theshoe is applied, cooperating means between one end of said lever and the support for adjusting the off position of the unmounted 1end of the shoe toactuated wedge cooperating with the lever and the web for maintaining the lever and the web in their relatively adjusted positions.

11. In braking mechanism, a support, a brake drum, a brake shoe for cooperation with the drum, said shoe comprising a web mounted at one end on the support for pivotal movement and for circumferential movement of the drum, a flange provided with a lining and extending over the major portion of the web and being secured to the portion of the web from an intermediate point to the free end of the web and so associated with the remaining portion of the web that it is free to move relatively to the web and outwardly toward the drum, means opmeans for maintaining the off position clearance between the drum and the lining carried by the iiange substantially constant, said means being so associated with the secured portion of the ange and the free portion of the ange that both portions will have their oi positions simultaneously adjusted toward the drum as wear occurs.

12. In braking mechanism, a support, a brake drum, a brake shoe for cooperation with the drum, said shoe comprising a web mounted at one end on the support for pivotal movement and for circumferential movement of the drum, a flange provided with a lining and extending over the major portion of the web and being secured to the portion of the web from an intermediate point to the free end of the web and so associated with the remaining portion of the web that it is free to move relatively to the web and outwardly toward the drum, means operable by circumferential movement of the web when the shoe is applied to the drum for forcing the free portion of the lining carrying ange toward the drum, a fixed stop carried by the support adjacent the free end of the web, a lever pivoted on the web and adapted to engage the stop when the shoe is a predetermined distance fromthe drum, means controlled by the wear of the lining for causing relative movement between the web and the lever, means for automatically maintaining the lever and the web in their relatively adjusted positions, and means operable by the lever when moved relatively to the web for moving the free portion of the ange outwardly toward the drum.

13. In braking mechanism, a support, a brake drum, a brake shoe for cooperation with the drum, said shoe comprising a web mounted at one end on the support for pivotal movement and for circumferential movement of the drum, a ange provided with a lining and extending over the major portion of the web and being secured to the portion of the web from an intermediate point to the free end of the web and so associated with the remaining portion of the web that it is free to move relatively to the web and outwardly toward the drum, means operable by circumferential movement of the web when the shoe is applied to the drum for forcing the free portion of the lining carrying flange to the drum, a fixed stop carried by the support adjacent the free end of the web, a lever pivotally mounted intermediate its ends on the web and having one end adapted to engage the stop when the shoe is a predetermined distance from the drum, means controlled by the wear of the lining for causing the lever to pivot relatively to the web, means for maintaining the lever and the web at their relatively adjusted positions, and connecting means between the other, end of the lever and the free portion of the flange for moving the latter outwardly toward the drum when the lever is moved as a result of wear of the lining.

14. In braking mechanism, a support, a brake drum, a brake shoe for cooperation with the drum, said shoe comprising a Web mounted at one provided with a lining and extending over the y major portion of the web and being secured to the portion of the web from an intermediate point to the free end of the web and so associated with the remaining portion of the web that it is free to move relatively to the web and outwardly toward the drum, means operable by circumferential movement of the web when the shoe is applied to the drum for forcing the free portion of the lining carrying ange toward the drum, a fixed stop carried by the support adjacent the free end of the web, a lever pivotally mounted intermediate its ends on the web and having one end adapted to engage the stop when the shoe is a predetermined distance from the drum, means controlled by the wear of the lining for causing the lever to pivot relatively to the web, spring-actuated wedge means for holding the lever in adjusted position with respect to the web, and connecting means between the other end of the lever and the free portion of the iange for moving the latter outwardly toward the drum when the lever is moved as a result of wear of the lining.

' STEVE SCHNELL. 

